Traditional masonry fireplaces designed to burn wood or coal as fuel are no longer being built in today's modern houses. These old style fireplaces are not particularly effective at heating the room in which they are located and they tend to be rather dirty due to the nature of the fuel being used and hence they require constant cleaning and general maintenance. The fireplaces are also susceptible to downdrafts through the venting chimney stack. A further disadvantage is that relatively large areas need to be set aside to store fuel for burning.
In view of the foregoing disadvantages of traditional masonry fireplaces, it is not surprising that there has been a move to cleaner and more efficient gas fireplaces. Generally, the newer style of gas fireplace comprises an insert that is fitted into a preformed cavity built into the wall of a dwelling and connected to a flexible venting duct that is already in place. Making the connection between the insert and the venting duct has in the past restricted the size and configuration of the insert. The insert has to be substantially smaller than the fireplace cavity since there has to be room about the insert to reach in and manoeuvre the venting duct to connect the duct to the insert. This is especially true of fireplace inserts being retro-fitted into older style fireplace cavities.